(a) Technical Field
The present invention relates to a method for preparing a hydrosilane using heteroatom-containing activated carbon, more particularly to a method for economically preparing a high-purity hydrosilane by redistribution of a chlorosilane using a heteroatom-containing activated carbon catalyst.
(b) Background Art
For preparation of a hydrosilane, a method of converting trichlorosilane to a hydrosilane such as dichlorosilane, monochlorosilane or silane by redistribution has been known from long ago.
For example, U.S. Pat. No. 2,732,280 introduced a method of preparing a hydrosilane by converting an alkyl trichlorosilane to an alkyl dichlorosilane or monosilane using a cyanamide catalyst. And, U.S. Pat. No. 4,018,871 disclosed a method of preparing a 10 mol % dichlorosilane in 6-7 hours from trichlorosilane using 10 w % of α-pyrrolidone as a catalyst.
However, these methods are inapplicable to large-scale production because a cyanamide monomer or a pyrrolidone monomer is used and, thus, it is difficult to establish a continuous process.
Later, U.S. Pat. No. 4,113,845 presented a method of preparing dichlorosilane and monosilane by disproportionation of trichlorosilane or dichlorosilane in a fixed bed reactor filled with an anion exchange resin containing a tertiary amine or a quaternary ammonium salt.
However, this method has the problems that the reaction temperature is limited to 150° C. or lower, deformation of the organic catalyst may occur because of low thermal stability and a quaternary ammonium salt produced from decomposition of the catalyst may lead to contamination of the reactor.
Meanwhile, U.S. Pat. No. 2,627,451 disclosed a method of preparing a hydrosilane by converting trichlorosilane to dichlorosilane with a yield of 1-10 mol % using an inorganic catalyst such as aluminum trichloride, iron trichloride or boron trifluoride.
However, this method requires a lot of energy, with the reaction temperature ranging from 250 to 450° C., and a high pressure has to be maintained in the reactor because the chlorosilanes have low boiling points. In addition, since the catalyst is a major contaminant of a silicon-based semiconductor, the main product prepared from the silane, an additional purification process is required during redistribution.